A 6 9 4 AGA ABSTRACTS ' GASTROENTEROLOGY, VOl. 108, NO. 4

• STRESS-STRAIN DISTRIBUTIONS IN THE GUINEA-PIG SMALL INTESTINE DETERMINED BY MEANS OF COMBINED IMPEDANCE PLAN1METRY-HIGH FREQUENCY ULTRASOUND. J.H. Storkholm, G.E. Villadsen, H.Grcgersen. Core Center of Gastrointeslinal Biomechanics and Motility, Institute of Experimental Clinical Research, Aarhus University Hospital.

Regional differences exist in the small intestine regarding motility patterns and flow properties. According to classical biomechanical .theory the luminal dimensions and the elastic properties arc important for the resistance to the flow of chyme. Previously, the compliance and wall tension were used as measures of tissue elasticity. However, these parameters do not take the wall thickness into account and they are dependent on the geometry. The stress-strain distributions would in this respect be a more appropriate parameter. Stress is the wall tension divided' by wall thickness.and strain is:the fractional change in the luminal circumference. The aim was to compare the passive elastic wall proparties in isolated segments of the duodenum, the jejunum and the distal ileum of the guinea- pig in an in-vitro set-up. The segments were immersed i n a Krebs-Ringer solution containing 10 -2 MgC12 to abolish smooth muscle contractile activityl Stepwise inflation of an intraluminal balloon, in which the c/oss-sectional area (CSA) was measured, provided the distension stimulus. The wall thickness was measured during distension by means of an A-mode 20 MHz ultrasound transducer. From the steady state values of wall thickness, internal radius and applied pressure we derived the stress-strain and the incremental elastic modulus-strain distributions of the segments. At the maximum induced pressure of 6 kPa the CSAs were 37.66+3.49 mm 2, 58.88+2.02 mm 2, and 73.31+3.21 mm 2 in the duodenum, jejunum and distal ileum, respectively. The wall thickness-pressure relations differed statistically significant between all the segments (p<0.01) with values of 0.19+0.01ram, 0.12+0.01 nun, and 0.11+0.01mm in the duodenum, jejunum and distal ileum, iespectively. The stress-strain distributions showed an exponential behaviour that fitted well to the equation Y=EXP(a+bX) with determination coefficients (r 2) of 0.97+0.01. The values of a (intercept with the X-axis) were differcnt between all the segments investigated (p<0.01). The slopes of the curves (b-values) were also different between the duodenal, the jejunal, and the distal ileal segments (p<0.05). In conclusion, the stress strain distributions show regional differences in the guinea-pig small intestine. The differences in luminal dimensions, wall thickness and in passive elastic properties correlate well with previous data on the regional flow properties of the small intestine.

The Relationship Between Stress Related Cardiac and Gastrointestinal Disorders. W.P. Stuppy, E. Charuvastra, J. Randolph, and W. Shell Beverly Hills, CA

Previous work indicated that stress related cardiac dysfunction and functional bowel disorder (FBD) were associated with bile flow, choleresis. Data was analyzed further to determine whether these phenomena were temporally related, suggest- ing a common etiopathQgenesis. The clinical records of 20 age, race, and sex matched patients with stress related FBD, biopsy proven gastro- esophageal reflux disease, and symptoms of cardiac disease with chest pain and palpitation or syncope were retrospectively reviewed. In each case 24 hour cardiac monitoring for bradyarrhythmia and ischemia had been performed concurrently with continuous esophagogastric pH analysis. Non- prandial choleresis was identified by typical episodes of gastric alkalinity. Episodes of sinus bradycardia (SB), periods of Wenckebach phenomenon, and ischemic events were found cosynchronous with nocturnal non-prandial and prandial choleresis.

Nuntber of Episodes SB Wenckebach Ischemia

N0n-prandial choleresis 38 6 14 -- Prandial choleresis 1 2 Ii Without choleresis 6 1 3

From this We conclude that stress related cardiac and bowel disorders are components of a much broader response, mediated through the effects of cholecystokinin, implying a ~global imbalance of the autonomic nervous system. It also supports the idea that coronary vasoconstrictive events are induced parasympathetically.

• D I S T U R B A N C E S IN A N O R E C T A L F U N C T I O N IN PATIENTS WITH DIABETES MELLITUS AND FAECAL INCONTINENCE. W.M. Sun. P. Katsinelos and N.W. Read. Department of Medicine, Royal Adelaide Hospital, Adelaide, SA 5000, Australia and Gastrointestinal Motility Unit, Centre for Human Nutrition, Northern General Hospital, Sheffield $5 7AU, U.K.

A comprehensive investigation of the different components of anorectal function was carried out ih 11 consecutive diabetic patients referred for investigation of faecal incontinence, and the results were compared with data from 20 healthy normal controls. Incontinent diabetics had lower basal anal pressure than normal control subjects (38+7 vs 60&_5 cmH20, p<0,005). During basal recording 6/11 patients showed profound regular oscillations in anal electrical activity and pressure with an amplitude of 10-40 cmH20 (median: 25 cmH20) and a frequency of 6- 10 cpm (median: 8 cpm). This type of activity was not seen in the normal controls (p<0.01). Eight diabetic patients also exhibited spontaneous transient anal relaxations with an amplitude of 15-50 cmH20 (median: 40 cmH20) and a duration of 15-720 sec (median: 60 see), and six of them experienced leakage as the anal pressure fell below the rectal pressUre. None of the controls showed spontaneous relaxations. The incontinent diabetic patients showed a greater tendency to exhibit repetitive rectal contractions in response to rectal distension and a lower rectal compliance [3.3-5.0 ml .cmH20 -1, (median: 4.2 ml.cmH20-!) vs normals: 5.6-7.1 ml .cmH20 "1, (median: 6.5 ml.cmH20=l); p<0.01]. Only one of them showed receptive relaxation of the rectum. During rectal distension, four patients showed no anal relaxation, the remainder exhibited poorly sustained relaxation at an abnormally high thresholds, but the residual pressures were lower than in controls and often fell below rectal pressure, whereupon leakage occurred. There was no significant difference in the distension thresholds for rectal sensation, but in 9/11 patients the perception of rectal sensation was delayed more than two seconds after rectal distensions. No normal subjects had delayed sensation. T h e squeeze pressure was lower in the incontinent diabetic patients than the controls (153+-31 vs 226+18 cmH20, p<0.05), and the external sphincter responses to increases in intra-abdominal pressure were attenuated (196+_16 vs 135+16 cmH20, p<O.05).

These results suggest that faecal incontinence in diabetic patients is multifactorial but the weakness and instability of the internal sphincter probably plays a crucial role.

THE E F F E C T S OF N I T R I C OXIDE ( N O ) ON INTRADUODENAL LIPID INDUCED PYLORIC MOTILITY IN HUMANS. W.M. Sun. S. Emery, Th. Lingenfelser, G.S. Hebbard, J. Morley, I. Dent, M. Horowitz. Department of Medicine, Royal Adelaide Hospital, Adelaide, SA 5000, Australia.

The retardation of gastric emptying induced by infusion of lipid into the small intestine is associated with suppression of antral pressure waves, stimulation of phasic pressure waves localised to the pylorus and basic pyloric pressure. Nitric oxide (NO) is an important inhibitory neurotransmitter of non-adrenergic, non-cholinergic neurones in the gut. We have evaluated the role of NO mechanisms in the control of pylofic motility. In 8 healthy male subjects (21-43 years) antropylorie pressures were measured with a manometric assembly incorporating 9 sideholes (spaced at 1.5cm intervals, spanning the antrum and proximal duodenum) and a pyloric sleeve sensor. Pressures were digitised and recorded on a Macintosh computer. The number and amplitude of phasic isolated pyloric pressure waves (IPPW) and basal pyloric pressure were evaluated. On two separate days, intraduodenal lipid infusion (10% Intralipid at Iml/min) was started 10 minutes after an episode of antral phase III activity (Time 0) and continued for 60 minutes. Either glyceryl tfinitrate (GTN) (600p.g) or placebo was given sublingually 20 minutes after start of the lipid infusion. The GTN took approximately 5 minutes to dissolved. The order of studies was randomised. Blood pressure and heart rate were monitored throughout the study. Dam are shown as median values and ranges.

Time (min~ 10-20 20-30 30-40 P GTN P GTN P QTN

Basal pyloric pressure (mmH~) 1(0-6) 3(0-8) 2(0-6) 0(0-0)* 3(2-7) 0(0-0)* IPPW (No) 5(2-8) 5(3-135 5(0-12) 6(0-11) 4(2-13) 5(1-10) IPPW amplitude tmmH~t) 23(9-71) 22(12-62) 20(12-50) 28(10-62) 21(11-50) 23(9-53)

P: Placebo; *: cfplacebo, p<0.001).

The tonic pyloric motor response to triglyceride was abolished by GTN (p<0.001) but had no significant effects on the number or amplitude of phasic isolated pylofie pressure waves. GTN has no significant effect on the blood pressure or heart rate.

These results suggest that NO mechanisms arc involved in the control of basal pyloric pressure in humans.